Presently commercially known equipment for examination of objects for detection of flaws by the use of magnetic fields involves the disposition of the object in a magnetic field and effecting mutual rotational movement as between the object and flaw sensors. The sensors sense magnetic fields and generate output signals responsively to the sensing of changes in the ambient magnetic field occasioned by flaws in the object. One type of such equipment, embodying the so-called flux leakage method, is seen in U.S. Pat. No. 3,854,085, commonly-assigned herewith. Other types of such equipment, of eddy-current and EMAT (electromagnetic acoustic transducer) variety, are to be seen in U.S. Pat. No. 4,449,408, also commonly-assigned herewith. Incorporating reference is made hereby to such commonly-assigned patents.
In commercial practice heretofore, involving equipment of such assignee, Magnetic Analysis Corporation, and others involved in magnetic field object flaw examination, it has been customary to rely upon flaw intelligence gathered, per individual relative revolution of object and sensor, to reach a determination of the existence of an object flaw. This practice is problematic, especially in high noise environments, in that magnetic and electrical noise can give rise to faulty identifications of flaws not actually present in the object.